Pressure-vacuum control valve



March 4, 1952 J. H. WIGGINS PRESSURE-VACUUM CONTROL VALVE Filed April 19, 1948 z I r/ I/v VENTOR, JOHN H. W/GG/NS, WBW

A TT'O/PNEY Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE PRESSURE-VACUUM CONTROL VALVE John H. Wiggins, Chicago, Ill.

Application April 19, 1948, Serial No. 22,013

4 Claims.

This invention relates to control valves of the kind that are used to provide pressure relief or vacuum relief for apparatus of the general type or kind that comprise a fluid storage space provided with a movable part that moves in one direction when the internal pressure of said fluid storage space increases beyond a certain approximate degree or amount, and moves in the opposite direction when the internal pressure of said fluid storage space diminishes or drops below a certain approximate degree or amount. One example of apparatus of the general type or kind referred to is liquid and gas storage tanks of the type in which the roof or top wall of the fluid storage space rises and falls in response to variations in the internal pressure of said storage space.

One object of my invention is to provide a pressure-vacuum valve of the general kind above mentioned, that is inexpensive to manufacture, and of such design that it comprises relatively few working parts, all of which are easily accessible from the exterior of the valve structure. Another object is to provide a pressure-vacuum valve having a control chamber equipped with a movable wall that functions either as a valve palate, or as an actuating device for a vent closure, and which moves so as to provide pressure relief or vacuum relief for the fluid storage space of the apparatus with which the valve is associated, due to or as a result of variations in excess of a certain approximate degree or amount, of the internal pressure of said storage space. Other objects and desirable features of my invention will be hereinafter pointed out.

The figure of the drawing is a vertical, transverse sectional view, of a pressure-vacuum control valve embodying my present invention.

In the drawings, the reference character A designates a fluid storage space formed by a container which is of such construction that its internal volume will decrease and increase as a result of variations in the internal pressure of the storage space A. The container just referred to may consist of the apparatus with which my improved control valve is used, such, for example, as a gas and/or liquid storage tank provided with a vertically-movable roof that rises and falls as the internal pressure of the storage space of the apparatus varies, or the said container may constitute a part of my improved control valve, in which event said container would be of relatively small dimensions, as compared with the container of the storage apparatus and connected up with same in such a way that the internal pressure (positive or minus) of the small container of the control valve would always be the same as the internal pressure (positive or minus) of the large container of the storage apparatus. The particular construction of the container which constitutes the fluid storage space A is immaterial. I have herein illustrated said container as being composed of a stationary tank or receptacle I, provided with a vertically-movable top or roof 2 equipped with a depending skirt 3 that projects downwardly into sealing liquid at confined in a reservoir 4 which surrounds the side wall of the tank I, the fluid that is confined in the storage space A being admitted to and withdrawn from same through a pipe 5 herein shown as projecting upwardly through the bottom of the tank I. Obviously, various other types and kinds of sealing means and sealing structures can be used in place of the above described liquid seal, for maintaining a tight joint between the stationary and movable portions l and 2, respectively, of the container which constitutes the fluid storage space A.

My improved pressure-vacuum valve is used to permit pressure to escape from the fluid space A to provide pressure relief for said space, and is also used to admit air or a gaseous medium to said space to provide vacuum relief for said space. In the form of my invention herein illustrated said valve comprises a control chamber B, mounted on or carried by the movable top portion 2 of the fluid space A in such a Way that it moves bodily with same, and constructed and arranged in such a manner that a variation in the internal pressure of the fluid space A will produce a corresponding variation in the internal pressure of said control chamber and cause a movable wall or movable portion 6 of said control chamber to function as a valve palate for a vent 1 leading from the fluid storage space A. I have herein illustrated the vent l as being formed by a verticallydisposed, tubular member attached to the movable top wall 2 of the fluid space A and projecting upwardly from same so as to form a combined inlet and outlet for the space A, which normally is closed by the previously mentioned movable wall 6 of the control chamber B. Said. movable Wall 6 constitutes the bottom of the control chamber B, and is arranged in opposed relation to a stationary top Wall 8 that is rigidly attached to the vent 1 by one or more brackets 9 on said vent. The side wall portion of the control chamber B is constructed in such amanner that it is capable of flexing or moving sufliciently to provide for the movement of the bottom wall 6 of the con- '16 in the control valve 6.

trol chamber and permit said bottom wall to move towards and away from the valve seat at the upper end of the vent l of the fluid space A. Usually, the side wall portion of the control chamber B will consist of an accordian-like structure, or a structure made of gas-tight fabric, such as a tubular member It, constructed of flexible material and attached at its upper and lower ends by clamping rings i l to flanges on the stationary top wall 8 and movable bottom wall 6 of the control chamber.

Means is provided for establishing communication at all times between the fluid space A and the interior of the control chamber B, and thus cause an increase or decrease in the internal pressure of the fluid space A to produce a corresponding increase or decrease in the internal pressure of the control chamber B. In the particular form of my invention, herein illustrated, said means consists of a duct l2 leading from the upper end of the control chamber B and attached to the vent l at a point below the upper end of said vent. Normally, the movable bottom wall 6 of the control chamber functions as a valve palate that cuts off communication between the atmosphere and the vent I leading from the fluid space A, During the normal functioning of the apparatus with which my improved valve is associated, it is necessary to open the vent i so as to provide pressure relief for the fluid space A, and in the form of my invention herein illustrated, this is effected by a mechanically-operated device constructed and arranged so that when the top wall 2 of the fluid space A rises or moves upwardly beyond a certain approximatepoint, due to an increase in the internal pressure of the fluid space A, said device will unseat the valve palate (the movable bottom wall 6 of the control chamber B) or move it away from the valve seat on the vent 1, and thus provide pressure relief for the fluid space A. I have herein illustrated the unseating device for the valve palate as consisting of a lever l3 pivotally mounted on a supporting arm I4 carried by the movable top wall 2 of the fluid space A, and arranged so as to normally occupy a substantially horizontal position, with its left hand end bearing upwardly on the underside of the valve palate 6 and its right hand end overlapped by a stationary bracket or abutment piece I5, attached to the liquid reservoir 4 on the side wall of the tank I, which constitutes the stationary lower portion of the fluid space A. In the drawing, for the sake of clarity, I have shown the left hand end of the valve actuating lever is as engaging the movable bottom wall 6 of the control chamber at a point slightly off center, but in practice, the inner end portion of the lever 13 would be constructed in the form of a yoke that straddles the vent I, and thus exerts upward pressure on the valve palate 8, without tending to tilt or tip the same. In order to permit condensate which may collect in the control chamber B to escape from said chamber, I form a port or drain opening l6 in the valve palate 6 at a point in alignment with the interior of the vent I. This enables the control chamber B to be effectively drained of condensate, simply by drilling a hole Obviously, said drain hole l6 must be of considerably smaller crosssectional area than the cross-sectional area of the fluid passageway l2 leading to the control chamber, in order to prevent the control chamber from losing its vacuum through the drain opening it. a Y 1 When the fluid space A is under pressure, a

4 similar pressure exists in the control chamber B, due to the connection between said space and chamber formed by the vent l and the duct l2. This pressure is exerted on the movable bottom wall 6 of the control chamber in a direction to hold said bottom wall tightly seated against the upper end of the vent l for the fluid space A. The movable top wall 2 of the fluid space A is capable of rising and falling, within certain limits, without effecting a change in the normal closed position of the bottom wall 6 of the control chamber B, or of the actuating lever l3 for said bottom wall, but if the internal pressure of the fluid space A increases beyond a certain approximate degree or amount, the top wall 2 of said space, together with the control chamber B, will rise or move upwardly as indicated by broken lines in the drawing, thereby causing the lever 13 to rock on its fulcrum and move the bottom wall 6 of the control chamber upwardly relatively to the stationary top wall of said chamber, thus unsealing or opening the vent I and relieving the internal pressure in the fluid space A. In other words, notwithstanding the fact that the control chamber B and valve actuating device 13 move upwardly bodily with the movable top wall 2 of the fluid space A, and at the same speed of travel as the top wall 2, movement of the bottom wall 6 relatively to the stationary top wall 8 of the control chamber is effected by the rocking action of the lever I3, resulting from the engagement of the stationary abutment member I5 with the right hand end of lever i3., In the structure shown in the drawing the left hand end portion of the lever l3 which engages the movable bottom wall 6 of the control chamber will rise or move upwardly about twice as fast as the top wall 2 of the fluid space A and the top wall 8 of the control chamber B, which is in rigid relationship with the top wall 2 of the fluid space. In so doing, the lever l3 moves the bottom wall 6 of the control chamber relatively to the vent I into the position shown in broken lines in the drawing.

Thereafter, when the movable top portion 2 of the fluid space A moves downwardly sufficiently to prevent the lever l3 from exerting an upward thrust on the bottom Wall of the control chamber B, said bottom wall resumes its normal position, in which it serves as a closure for the vent 1. If the internal pressure of the fluid space A diminishes to such an extent or degree that the movable top portion of the container which constitutes the fluid space A and composed of the roof 2 and skirt 3, moves downwardly into its extreme lowermost position, as indicated by the dot and dash lines designated by 3* in the drawing, a vacuum or minus pressure will be created in the fluid storage space A. Similarly, a vacuum will be created in the control chamber B, with the result that the bottom wall 6 of said control chamber will be moved by said vacuum in an upward direction, or in a direction to open the vent l and permit air to enter the vapor space A, so as to provide vacuum relief for same. It is seen that, normally, if the valve 6 opened, the vacuum in the control chamber B would be lost, and said valve would chatter, but inmy improved valve structure, the duct l2 which leads from the vent l to the interior of the control chamber B, maintains the vacuum-in the control chamber, with the result that during the operation of providing vacuum relief for the fluid space A, the valve will remain in its open position, without chattering, or pounding against its valve seat.

A valve structure of the kind above described is inexpensive to manufacture; it is reliable in operation; and it is easy to service, as all of the movable parts of same are on the exterior of the structure, where they are easily accessible. While I prefer to construct the movable bottom wall 6 of the control chamber B, so that it constitutes the valve palate and acts directly on the valve seat surrounding a port that serves as a combined inlet and outlet for the fluid space A, I wish it to be understood that a valve palate or part separate and distinct from the movable bottom wall 6 of the control chamber but attached to same, could be used to control the vent 7 without departing from the spirit of my invention. In other words, instead of having the bottom wall 6 of the control chamber act itself as the palate or closure for the vent l, a separate closure could be provided for said vent and said separate closure could be attached to the movable bottom wall 6 of the control chamber B in such a way that it would be held seated by pressure in the control chamber; it would be opened or unseated by movement of the bottom wall 6 of the control chamber relatively to the stationary top wall 8 in the event the internal pressure of the fluid space A exceeds a certain degree or amount; and it would be opened or unseated so as to provide vacuum relief for the fluid space A when the control chamber is under a minus pressure sufficient to move the bottom wall 6 of said chamber upwardly towards the stationary top wall 8.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a valve, the combination of a vent for a fluid chamber, carried by a part of said fluid chamber that is adapted to move bodily in opposite directions in response to variations in the internal pressure of said fluid chamber, and a control chamber combined with said vent so as to move with same and provided with two opposed walls and a flexible portion interposed between said opposed walls, one of said walls being stationary with respect to said vent and said other wall being movable and disposed in such relationship with said vent so as to constitute a closure for said vent that is capable of moving relatively to said vent, into and out of open position.

2. The combination of a sealed fluid container provided with a vertically-movable top portion that rises and falls in response to variations in the internal pressure of said container, a vent on said top portion, a control chamber carried by said movable top portion and composed of a stationary top wall, a movable bottom wall and a flexible side wall, said movable bottom wall being adapted to function as a control device for opening and closing said vent, a fluid passageway for establishing communication at all times between said container and said control chamber, and means rendered operative by the upward movement of the top portion of said container, beyond a certain approximate point, for moving the bottom wall of said control chamber to effect pressure relief for the fluid space of said eontainer.

3. The combination of a container adapted to hold a fluid and provided with a verticallymovable roof or top portion, a vent for said container mounted on said roof or top portion, a control chamber carried by said roof and provided with a movable valve palate that is normally seated on said vent, a fluid passageway between the interior of said control chamber and said container, an actuating device for said valve palate carried by said roof, and means whereby upward movement of said roof beyond a certain approximate point or degree causes said valve palate to be unseated.

4. The combination of a fluid container, composed of a stationary tank that is adapted to hold fluid, a vertically-movable roof for said tank, a sealing means between said roof and tank, a

vertically-disposed, tubular vent for said container mounted on said roof and provided with a valve seat, a control chamber carried by said roof, a fluid passageway between said container and the interior of said control chamber, said control chamber having a flexible side wall and a movable bottom wall that serves as a control valve for said vent, a rock lever mounted on the vertically-movable roof of said container, and means rendered operative by upward movement of said roof beyond a certain approximate point for causing said lever to move the bottom wall of the control chamber into a position to open said vent so as to provide pressure relief for said container.

JOHN H. WIGGINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,013,643 Curse Jan. 2, 1912 1,651,971 Shield Dec. 6, 1927 1,652,793 Perry Dec. 13, 1927 1,678,700 McEwan July 31, 1928 1,905,583 Giesler Apr. 25, 1933 1,917,623 Wiggins July 11, 1933 2,050,685 Wiggins Aug. 11, 1936 2,168,891 Wiggins Aug. 8, 1939 2,171,168 Swank Aug. 29, 1939 2,215,308 Wiggins Sept. 17, 1940 2,313,855 Wiggins Mar. 16, 1943 2,317,923 Lebo et al Apr. 27, 1943 

